LYON, France, November 06, 2007 /PRNewswire-FirstCall/ -- Sanofi
Pasteur, the vaccines division of sanofi-aventis Group, announced
today positive results in the development of a vaccine for the
global prevention of dengue fever, one of the most widespread
tropical diseases. The results are being presented today at the
American Society of Tropical Medicine and Hygiene (ASTMH)'s 56th
annual meeting held in Philadelphia, Pennsylvania, USA.

These results have prompted Sanofi Pasteur to immediately expand
ongoing clinical trials in Asia and Latin America. Submission to
health authorities for registration is anticipated in 2012.

"Sanofi Pasteur made research for a vaccine against dengue fever
one of its top priorities by investing in the most promising
technology and dedicating top scientists to this lifesaving
project," said Wayne Pisano, President and Chief Executive Officer
of Sanofi Pasteur. "Sanofi Pasteur's goal is to make dengue fever a
vaccine-preventable disease as quickly as possible with a vaccine
available to people living in endemic countries or traveling to
tropical destinations."

Immunization with Sanofi Pasteur's tetravalent dengue candidate
vaccine generated a sero-neutralizing antibody response against all
four serotypes of the virus responsible for dengue fever in 100
percent of adults who participated in a trial in the United
States.(1)

"Developing a dengue vaccine has been a major challenge for over
a decade, and we are very pleased with the breakthrough progress
made by Sanofi Pasteur with its tetravalent dengue vaccine," said
Harold Margolis, MD, Director of the Pediatric Dengue Vaccine
Initiative (PDVI). "We believe this moves the world closer to a
dengue vaccine that will be available for people who most need
it."

Dengue fever is a mosquito-borne disease affecting up to 100
million people each year and resulting in 24,000 deaths, mostly
among children, according to estimates from the World Health
Organization (WHO).(2),(3) Overall, the disease is a potential
threat for close to half the world's population. Dengue disease if
often cyclical and causes spikes in demand on local medical
resources and places tremendous pressure on strained hospitals and
clinics located in endemic countries.

Dengue fever occurs mostly in tropical and subtropical countries
and it is spreading to new parts of the globe each year. For
example, outbreaks recently have been observed in Paraguay and the
Middle East. In addition, dengue affects countries such as
Australia (Queensland) and the United States (Puerto Rico,
Texas-Mexico border, Hawaii and the US-affiliated Pacific Islands).
A substantial number of people traveling to endemic regions are
also infected each year.

Sanofi Pasteur's tetravalent dengue candidate vaccine is based
on a new technology incorporating the protein envelopes that
provide immunity against the four virus types responsible for
dengue fever and the most severe forms of the disease-dengue
hemorrhagic fever and dengue shock syndrome.

About Sanofi-aventis

Sanofi-aventis, a leading global pharmaceutical company,
discovers, develops and distributes therapeutic solutions to
improve the lives of everyone. Sanofi-aventis is listed in Paris
and in New York .

Sanofi Pasteur, the vaccines division of sanofi-aventis Group,
provided more than a billion doses of vaccine in 2006, making it
possible to immunize more than 500 million people across the globe.
A world leader in the vaccine industry, Sanofi Pasteur offers the
broadest range of vaccines protecting against 20 infectious
diseases. The company's heritage, to create vaccines that protect
life, dates back more than a century. Sanofi Pasteur is the largest
company entirely dedicated to vaccines. Every day, the company
invests more than EUR1 million in research and development. For
more information, please visit: www.sanofipasteur.com or
http://www.sanofipasteur.us

Forward Looking Statements

This press release contains forward-looking statements as
defined in the Private Securities Litigation Reform Act of 1995, as
amended. Forward-looking statements are statements that are not
historical facts. These statements include financial projections
and estimates and their underlying assumptions, statements
regarding plans, objectives, intentions and expectations with
respect to future events, operations, products and services, and
statements regarding future performance. Forward-looking statements
are generally identified by the words "expects," "anticipates,"
"believes," "intends," "estimates," "plans" and similar
expressions. Although sanofi-aventis' management believes that the
expectations reflected in such forward-looking statements are
reasonable, investors are cautioned that forward-looking
information and statements are subject to various risks and
uncertainties, many of which are difficult to predict and generally
beyond the control of sanofi-aventis, that could cause actual
results and developments to differ materially from those expressed
in, or implied or projected by, the forward-looking information and
statements. These risks and uncertainties include those discussed
or identified in the public filings with the SEC and the AMF made
by sanofi-aventis, including those listed under "Risk Factors" and
"Cautionary Statement Regarding Forward-Looking Statements" in
sanofi-aventis' annual report on Form 20-F for the year ended
December 31, 2006. Other than as required by applicable law,
sanofi-aventis does not undertake any obligation to update or
revise any forward-looking information or statements.

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